This invention relates to the field of telecommunications, and more particularly to telephone services for customers using multiple lines.
The use of multiple lines by telephone subscribers is now commonplace. In addition to lines within the household, subscribers frequently rely on cellular lines, lines in office locations, lines at locations near the home, and lines at relatives' or friends' homes. Even more common is the use of multiple lines by businesses.
Whether the multiple lines relate to residential or business use, the individual who generally answers the call can often be found at destinations other than the primary destination (i.e., the destination first dialed by the calling party). Further, the individual's primary destination may be engaged for long periods of time due to extended voice or data connections. For these and other reasons, it is desirable to have a service which can automatically ring other secondary destinations where the answering individual may be present. Such a service might dial other numbers to search for the answering party at one or more secondary destinations. The service would be useful, for example, when the primary reference is busy or when no answer conditions are encountered. The caller could hunt among multiple destinations without having preexisting knowledge of phone numbers at secondary destinations where the subscriber may be present.
Call-forwarding is an example of an application that permits, at the subscriber's initiation, an incoming call to ring to a secondary destination. Standard call-forwarding has several benefits which provide for increased subscriber mobility and flexibility. For instance, many call-forwarding applications are available on a wide area basis. These applications, in particular, enable a subscriber to forward telephone calls to any secondary destination which can be accessed from the central office via the Publicly Switched Telephone Network (PSTN). Such destinations include different twisted pair lines, cellular lines, pagers, and other media. With standard call-forwarding, few limitations on available secondary destinations exist, and no dedicated preprogramming of specific destinations is necessary.
Another feature of some call-forwarding applications permits the subscriber to remotely forward calls from the caller's primary destination to a secondary destination. With this feature, the subscriber can forward incoming calls while located at a remote location; he or she need not be present at the primary destination to initiate the forwarding process. The benefits of this feature are self evident--a subscriber who desires to forward telephone calls typically is not located at the primary destination but rather is at a secondary destination where he or she wishes to receive incoming calls. Hence, a subscriber has the versatility to forward incoming calls regardless of the subscriber's physical location.
A typical call-forwarding method alerts multiple destinations using a single origination. This means that the call-forwarding method is initiated by a single phone call to the primary destination. With this method, a busy or no-answer condition at the primary destination triggers the ringing cycle to commence at a secondary destination. FIG. 1a illustrates a timeline in accordance with this method. Call attempt one is initiated by the user dialing the primary destination. Where a busy signal or a no-answer condition exists at the primary destination, dialing is initiated to a secondary destination (call attempt two). The X in FIG. 1a indicates a successful connection between the caller and a person answering at the secondary destination.
With this method, call attempt one is terminated upon the initiation of call attempt two. Thus, an individual at the primary destination who takes too long to answer will miss the call. This termination of the ringing at the primary destination highlights a common problem associated with standard call-forwarding. Namely, the method requires the users and offerors of such services to predetermine the permissible number of ring cycles associated with the call attempt to the primary destination. This predetermined number, which may reside in the software program executing the call-forwarding algorithm and which may be programmable by the subscriber, dictates the number of times that the primary destination will ring before the connection is terminated in favor of call attempt two. Setting the number too low may result in calls never being answered at the primary destination, thereby eliminating much of the utility of call-forwarding. Typically, in this case, an individual near the phone at the primary destination runs to answer the call but is not fast enough. Moreover, where an answering machine or a call answer service is connected to the primary destination, call-forwarding may defeat the purpose of these utilities by terminating the ringing of the primary destination before the answering machine initiates an automated pickup. Conversely, setting the number of ring cycles too high may lead to an abandoned effort by the calling party before a call is ever initiated to a secondary destination. This situation would likewise defeat much of the utility of call-forwarding.
An alternative prior art method, which allows multiple terminals with a shared directory number to be alerted simultaneously, is shown in FIG. 1b. In such a method, two or more call attempts are concurrently made, and the first answering party is connected to the caller. When this connection occurs in call attempt two, call attempt one is terminated. Schemes like this one are typically used by attendant pools or by call directors that support call centers. When one attendant picks up, all other call attempts are shut down and subsequent pickups do not participate in the call. One characteristic of this arrangement is that it does not give primacy to a single destination. Thus this method is not appropriate for accommodating situations where the subscriber desires most calls to be handled by a primary destination. As an illustration, a subscriber may have a line in his household but may be physically present at a relative's home. With the method of FIG. 1b, a caller dialing the primary destination would automatically initiate ringing at both the subscriber's home and the relative's home. Among other problems, this scheme creates unnecessary ringing cycles at destinations where an answerer is less likely to pick up. The disadvantages of this approach are equally apparent in a business or office setting.
Other methods have been proposed in the literature which provide for delayed ringing on one telephone number which appears on two stations. (National ISDN Feature Handbook, 5ESS-2000 SWITCH, Issue 2.00 2.1-95 (Sep. 1995)). These applications, however, are limited to a predefined group of dedicated terminals and have no remote or wide area capability. Certain centrex applications, for instance, employ a preprogrammed extension dialing feature for an office building, and provide for call-forwarding capability between extensions in the building. However, these methods lack the versatility of standard call forwarding systems which are generally more global and which are not restricted to a preprogrammed set of destinations. Unfortunately, current call-forwarding algorithms possess other shortcomings, discussed above, which greatly limit their overall utility.
It is therefore an object of the invention to disclose a method for hunting among two or more destinations in a system having multiple telephone lines, which method possesses wide area capability and which overcomes disadvantages associated with existing methods.
Another object of the invention to disclose an improved method for hunting among a plurality of destinations in a telephone system wherein multipoint connections are employed for the benefit of a subscriber.
Further objects will be apparent to those skilled in the art upon perusal of this disclosure, claims, and drawings.